/*
 * ccp.c - PPP Compression Control Protocol.
 *
 * Copyright (c) 1994-2002 Paul Mackerras. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. The name(s) of the authors of this software must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission.
 *
 * 3. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by Paul Mackerras
 *     <paulus@samba.org>".
 *
 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "netif/ppp/ppp_opts.h"
#if PPP_SUPPORT &&                                                             \
    CCP_SUPPORT /* don't build if not configured for use in lwipopts.h */

#include <stdlib.h>
#include <string.h>

#include "netif/ppp/ppp_impl.h"

#include "netif/ppp/ccp.h"
#include "netif/ppp/fsm.h"

#if MPPE_SUPPORT
#include "netif/ppp/lcp.h"  /* lcp_close(), lcp_fsm */
#include "netif/ppp/mppe.h" /* mppe_init() */
#endif                      /* MPPE_SUPPORT */

/*
 * Unfortunately there is a bug in zlib which means that using a
 * size of 8 (window size = 256) for Deflate compression will cause
 * buffer overruns and kernel crashes in the deflate module.
 * Until this is fixed we only accept sizes in the range 9 .. 15.
 * Thanks to James Carlson for pointing this out.
 */
#define DEFLATE_MIN_WORKS 9

/*
 * Command-line options.
 */
#if PPP_OPTIONS
static int setbsdcomp(char **);
static int setdeflate(char **);
static char bsd_value[8];
static char deflate_value[8];

/*
 * Option variables.
 */
#if MPPE_SUPPORT
bool refuse_mppe_stateful = 1; /* Allow stateful mode? */
#endif                         /* MPPE_SUPPORT */

static option_t ccp_option_list[] = {
    {"noccp", o_bool, &ccp_protent.enabled_flag, "Disable CCP negotiation"},
    {"-ccp", o_bool, &ccp_protent.enabled_flag, "Disable CCP negotiation",
     OPT_ALIAS},

    {"bsdcomp", o_special, (void *)setbsdcomp,
     "Request BSD-Compress packet compression",
     OPT_PRIO | OPT_A2STRVAL | OPT_STATIC, bsd_value},
    {"nobsdcomp", o_bool, &ccp_wantoptions[0].bsd_compress,
     "don't allow BSD-Compress", OPT_PRIOSUB | OPT_A2CLR,
     &ccp_allowoptions[0].bsd_compress},
    {"-bsdcomp", o_bool, &ccp_wantoptions[0].bsd_compress,
     "don't allow BSD-Compress", OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLR,
     &ccp_allowoptions[0].bsd_compress},

    {"deflate", o_special, (void *)setdeflate, "request Deflate compression",
     OPT_PRIO | OPT_A2STRVAL | OPT_STATIC, deflate_value},
    {"nodeflate", o_bool, &ccp_wantoptions[0].deflate,
     "don't allow Deflate compression", OPT_PRIOSUB | OPT_A2CLR,
     &ccp_allowoptions[0].deflate},
    {"-deflate", o_bool, &ccp_wantoptions[0].deflate,
     "don't allow Deflate compression", OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLR,
     &ccp_allowoptions[0].deflate},

    {"nodeflatedraft", o_bool, &ccp_wantoptions[0].deflate_draft,
     "don't use draft deflate #", OPT_A2COPY,
     &ccp_allowoptions[0].deflate_draft},

    {"predictor1", o_bool, &ccp_wantoptions[0].predictor_1,
     "request Predictor-1", OPT_PRIO | 1},
    {"nopredictor1", o_bool, &ccp_wantoptions[0].predictor_1,
     "don't allow Predictor-1", OPT_PRIOSUB | OPT_A2CLR,
     &ccp_allowoptions[0].predictor_1},
    {"-predictor1", o_bool, &ccp_wantoptions[0].predictor_1,
     "don't allow Predictor-1", OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLR,
     &ccp_allowoptions[0].predictor_1},

#if MPPE_SUPPORT
    /* MPPE options are symmetrical ... we only set wantoptions here */
    {"require-mppe", o_bool, &ccp_wantoptions[0].mppe,
     "require MPPE encryption", OPT_PRIO | MPPE_OPT_40 | MPPE_OPT_128},
    {"+mppe", o_bool, &ccp_wantoptions[0].mppe, "require MPPE encryption",
     OPT_ALIAS | OPT_PRIO | MPPE_OPT_40 | MPPE_OPT_128},
    {"nomppe", o_bool, &ccp_wantoptions[0].mppe, "don't allow MPPE encryption",
     OPT_PRIO},
    {"-mppe", o_bool, &ccp_wantoptions[0].mppe, "don't allow MPPE encryption",
     OPT_ALIAS | OPT_PRIO},

    /* We use ccp_allowoptions[0].mppe as a junk var ... it is reset later */
    {"require-mppe-40", o_bool, &ccp_allowoptions[0].mppe,
     "require MPPE 40-bit encryption", OPT_PRIO | OPT_A2OR | MPPE_OPT_40,
     &ccp_wantoptions[0].mppe},
    {"+mppe-40", o_bool, &ccp_allowoptions[0].mppe,
     "require MPPE 40-bit encryption", OPT_PRIO | OPT_A2OR | MPPE_OPT_40,
     &ccp_wantoptions[0].mppe},
    {"nomppe-40", o_bool, &ccp_allowoptions[0].mppe,
     "don't allow MPPE 40-bit encryption",
     OPT_PRIOSUB | OPT_A2CLRB | MPPE_OPT_40, &ccp_wantoptions[0].mppe},
    {"-mppe-40", o_bool, &ccp_allowoptions[0].mppe,
     "don't allow MPPE 40-bit encryption",
     OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLRB | MPPE_OPT_40,
     &ccp_wantoptions[0].mppe},

    {"require-mppe-128", o_bool, &ccp_allowoptions[0].mppe,
     "require MPPE 128-bit encryption", OPT_PRIO | OPT_A2OR | MPPE_OPT_128,
     &ccp_wantoptions[0].mppe},
    {"+mppe-128", o_bool, &ccp_allowoptions[0].mppe,
     "require MPPE 128-bit encryption",
     OPT_ALIAS | OPT_PRIO | OPT_A2OR | MPPE_OPT_128, &ccp_wantoptions[0].mppe},
    {"nomppe-128", o_bool, &ccp_allowoptions[0].mppe,
     "don't allow MPPE 128-bit encryption",
     OPT_PRIOSUB | OPT_A2CLRB | MPPE_OPT_128, &ccp_wantoptions[0].mppe},
    {"-mppe-128", o_bool, &ccp_allowoptions[0].mppe,
     "don't allow MPPE 128-bit encryption",
     OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLRB | MPPE_OPT_128,
     &ccp_wantoptions[0].mppe},

    /* strange one; we always request stateless, but will we allow stateful? */
    {"mppe-stateful", o_bool, &refuse_mppe_stateful, "allow MPPE stateful mode",
     OPT_PRIO},
    {"nomppe-stateful", o_bool, &refuse_mppe_stateful,
     "disallow MPPE stateful mode", OPT_PRIO | 1},
#endif /* MPPE_SUPPORT */

    {NULL}};
#endif /* PPP_OPTIONS */

/*
 * Protocol entry points from main code.
 */
static void ccp_init(ppp_pcb *pcb);
static void ccp_open(ppp_pcb *pcb);
static void ccp_close(ppp_pcb *pcb, const char *reason);
static void ccp_lowerup(ppp_pcb *pcb);
static void ccp_lowerdown(ppp_pcb *pcb);
static void ccp_input(ppp_pcb *pcb, u_char *pkt, int len);
static void ccp_protrej(ppp_pcb *pcb);
#if PRINTPKT_SUPPORT
static int ccp_printpkt(const u_char *p, int plen,
                        void (*printer)(void *, const char *, ...), void *arg);
#endif /* PRINTPKT_SUPPORT */
#if PPP_DATAINPUT
static void ccp_datainput(ppp_pcb *pcb, u_char *pkt, int len);
#endif /* PPP_DATAINPUT */

const struct protent ccp_protent = {PPP_CCP,
                                    ccp_init,
                                    ccp_input,
                                    ccp_protrej,
                                    ccp_lowerup,
                                    ccp_lowerdown,
                                    ccp_open,
                                    ccp_close,
#if PRINTPKT_SUPPORT
                                    ccp_printpkt,
#endif /* PRINTPKT_SUPPORT */
#if PPP_DATAINPUT
                                    ccp_datainput,
#endif /* PPP_DATAINPUT */
#if PRINTPKT_SUPPORT
                                    "CCP",
                                    "Compressed",
#endif /* PRINTPKT_SUPPORT */
#if PPP_OPTIONS
                                    ccp_option_list,
                                    NULL,
#endif /* PPP_OPTIONS */
#if DEMAND_SUPPORT
                                    NULL,
                                    NULL
#endif /* DEMAND_SUPPORT */
};

/*
 * Callbacks for fsm code.
 */
static void ccp_resetci(fsm *);
static int ccp_cilen(fsm *);
static void ccp_addci(fsm *, u_char *, int *);
static int ccp_ackci(fsm *, u_char *, int);
static int ccp_nakci(fsm *, u_char *, int, int);
static int ccp_rejci(fsm *, u_char *, int);
static int ccp_reqci(fsm *, u_char *, int *, int);
static void ccp_up(fsm *);
static void ccp_down(fsm *);
static int ccp_extcode(fsm *, int, int, u_char *, int);
static void ccp_rack_timeout(void *);
static const char *method_name(ccp_options *, ccp_options *);

static const fsm_callbacks ccp_callbacks = {
    ccp_resetci, ccp_cilen, ccp_addci, ccp_ackci,   ccp_nakci,
    ccp_rejci,   ccp_reqci, ccp_up,    ccp_down,    NULL,
    NULL,        NULL,      NULL,      ccp_extcode, "CCP"};

/*
 * Do we want / did we get any compression?
 */
static int ccp_anycompress(ccp_options *opt) {
  return (0
#if DEFLATE_SUPPORT
          || (opt)->deflate
#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT
          || (opt)->bsd_compress
#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT
          || (opt)->predictor_1 || (opt)->predictor_2
#endif /* PREDICTOR_SUPPORT */
#if MPPE_SUPPORT
          || (opt)->mppe
#endif /* MPPE_SUPPORT */
  );
}

/*
 * Local state (mainly for handling reset-reqs and reset-acks).
 */
#define RACK_PENDING 1 /* waiting for reset-ack */
#define RREQ_REPEAT 2  /* send another reset-req if no reset-ack */

#define RACKTIMEOUT 1 /* second */

#if PPP_OPTIONS
/*
 * Option parsing
 */
static int setbsdcomp(argv)
char **argv;
{
  int rbits, abits;
  char *str, *endp;

  str = *argv;
  abits = rbits = strtol(str, &endp, 0);
  if (endp != str && *endp == ',') {
    str = endp + 1;
    abits = strtol(str, &endp, 0);
  }
  if (*endp != 0 || endp == str) {
    option_error("invalid parameter '%s' for bsdcomp option", *argv);
    return 0;
  }
  if ((rbits != 0 && (rbits < BSD_MIN_BITS || rbits > BSD_MAX_BITS)) ||
      (abits != 0 && (abits < BSD_MIN_BITS || abits > BSD_MAX_BITS))) {
    option_error("bsdcomp option values must be 0 or %d .. %d", BSD_MIN_BITS,
                 BSD_MAX_BITS);
    return 0;
  }
  if (rbits > 0) {
    ccp_wantoptions[0].bsd_compress = 1;
    ccp_wantoptions[0].bsd_bits = rbits;
  } else
    ccp_wantoptions[0].bsd_compress = 0;
  if (abits > 0) {
    ccp_allowoptions[0].bsd_compress = 1;
    ccp_allowoptions[0].bsd_bits = abits;
  } else
    ccp_allowoptions[0].bsd_compress = 0;
  ppp_slprintf(bsd_value, sizeof(bsd_value), rbits == abits ? "%d" : "%d,%d",
               rbits, abits);

  return 1;
}

static int setdeflate(argv)
char **argv;
{
  int rbits, abits;
  char *str, *endp;

  str = *argv;
  abits = rbits = strtol(str, &endp, 0);
  if (endp != str && *endp == ',') {
    str = endp + 1;
    abits = strtol(str, &endp, 0);
  }
  if (*endp != 0 || endp == str) {
    option_error("invalid parameter '%s' for deflate option", *argv);
    return 0;
  }
  if ((rbits != 0 && (rbits < DEFLATE_MIN_SIZE || rbits > DEFLATE_MAX_SIZE)) ||
      (abits != 0 && (abits < DEFLATE_MIN_SIZE || abits > DEFLATE_MAX_SIZE))) {
    option_error("deflate option values must be 0 or %d .. %d",
                 DEFLATE_MIN_SIZE, DEFLATE_MAX_SIZE);
    return 0;
  }
  if (rbits == DEFLATE_MIN_SIZE || abits == DEFLATE_MIN_SIZE) {
    if (rbits == DEFLATE_MIN_SIZE)
      rbits = DEFLATE_MIN_WORKS;
    if (abits == DEFLATE_MIN_SIZE)
      abits = DEFLATE_MIN_WORKS;
    warn("deflate option value of %d changed to %d to avoid zlib bug",
         DEFLATE_MIN_SIZE, DEFLATE_MIN_WORKS);
  }
  if (rbits > 0) {
    ccp_wantoptions[0].deflate = 1;
    ccp_wantoptions[0].deflate_size = rbits;
  } else
    ccp_wantoptions[0].deflate = 0;
  if (abits > 0) {
    ccp_allowoptions[0].deflate = 1;
    ccp_allowoptions[0].deflate_size = abits;
  } else
    ccp_allowoptions[0].deflate = 0;
  ppp_slprintf(deflate_value, sizeof(deflate_value),
               rbits == abits ? "%d" : "%d,%d", rbits, abits);

  return 1;
}
#endif /* PPP_OPTIONS */

/*
 * ccp_init - initialize CCP.
 */
static void ccp_init(ppp_pcb *pcb) {
  fsm *f = &pcb->ccp_fsm;

  f->pcb = pcb;
  f->protocol = PPP_CCP;
  f->callbacks = &ccp_callbacks;
  fsm_init(f);

#if 0  /* Not necessary, everything is cleared in ppp_new() */
    memset(wo, 0, sizeof(*wo));
    memset(go, 0, sizeof(*go));
    memset(ao, 0, sizeof(*ao));
    memset(ho, 0, sizeof(*ho));
#endif /* 0 */

#if DEFLATE_SUPPORT
  wo->deflate = 1;
  wo->deflate_size = DEFLATE_MAX_SIZE;
  wo->deflate_correct = 1;
  wo->deflate_draft = 1;
  ao->deflate = 1;
  ao->deflate_size = DEFLATE_MAX_SIZE;
  ao->deflate_correct = 1;
  ao->deflate_draft = 1;
#endif /* DEFLATE_SUPPORT */

#if BSDCOMPRESS_SUPPORT
  wo->bsd_compress = 1;
  wo->bsd_bits = BSD_MAX_BITS;
  ao->bsd_compress = 1;
  ao->bsd_bits = BSD_MAX_BITS;
#endif /* BSDCOMPRESS_SUPPORT */

#if PREDICTOR_SUPPORT
  ao->predictor_1 = 1;
#endif /* PREDICTOR_SUPPORT */
}

/*
 * ccp_open - CCP is allowed to come up.
 */
static void ccp_open(ppp_pcb *pcb) {
  fsm *f = &pcb->ccp_fsm;
  ccp_options *go = &pcb->ccp_gotoptions;

  if (f->state != PPP_FSM_OPENED)
    ccp_set(pcb, 1, 0, 0, 0);

  /*
   * Find out which compressors the kernel supports before
   * deciding whether to open in silent mode.
   */
  ccp_resetci(f);
  if (!ccp_anycompress(go))
    f->flags |= OPT_SILENT;

  fsm_open(f);
}

/*
 * ccp_close - Terminate CCP.
 */
static void ccp_close(ppp_pcb *pcb, const char *reason) {
  fsm *f = &pcb->ccp_fsm;
  ccp_set(pcb, 0, 0, 0, 0);
  fsm_close(f, reason);
}

/*
 * ccp_lowerup - we may now transmit CCP packets.
 */
static void ccp_lowerup(ppp_pcb *pcb) {
  fsm *f = &pcb->ccp_fsm;
  fsm_lowerup(f);
}

/*
 * ccp_lowerdown - we may not transmit CCP packets.
 */
static void ccp_lowerdown(ppp_pcb *pcb) {
  fsm *f = &pcb->ccp_fsm;
  fsm_lowerdown(f);
}

/*
 * ccp_input - process a received CCP packet.
 */
static void ccp_input(ppp_pcb *pcb, u_char *p, int len) {
  fsm *f = &pcb->ccp_fsm;
  ccp_options *go = &pcb->ccp_gotoptions;
  int oldstate;

  /*
   * Check for a terminate-request so we can print a message.
   */
  oldstate = f->state;
  fsm_input(f, p, len);
  if (oldstate == PPP_FSM_OPENED && p[0] == TERMREQ &&
      f->state != PPP_FSM_OPENED) {
    ppp_notice(("Compression disabled by peer."));
#if MPPE_SUPPORT
    if (go->mppe) {
      ppp_error(("MPPE disabled, closing LCP"));
      lcp_close(pcb, "MPPE disabled by peer");
    }
#endif /* MPPE_SUPPORT */
  }

  /*
   * If we get a terminate-ack and we're not asking for compression,
   * close CCP.
   */
  if (oldstate == PPP_FSM_REQSENT && p[0] == TERMACK && !ccp_anycompress(go))
    ccp_close(pcb, "No compression negotiated");
}

/*
 * Handle a CCP-specific code.
 */
static int ccp_extcode(fsm *f, int code, int id, u_char *p, int len) {
  ppp_pcb *pcb = f->pcb;
  LWIP_UNUSED_ARG(p);
  LWIP_UNUSED_ARG(len);

  switch (code) {
  case CCP_RESETREQ:
    if (f->state != PPP_FSM_OPENED)
      break;
    ccp_reset_comp(pcb);
    /* send a reset-ack, which the transmitter will see and
       reset its compression state. */
    fsm_sdata(f, CCP_RESETACK, id, NULL, 0);
    break;

  case CCP_RESETACK:
    if ((pcb->ccp_localstate & RACK_PENDING) && id == f->reqid) {
      pcb->ccp_localstate &= ~(RACK_PENDING | RREQ_REPEAT);
      UNTIMEOUT(ccp_rack_timeout, f);
      ccp_reset_decomp(pcb);
    }
    break;

  default:
    return 0;
  }

  return 1;
}

/*
 * ccp_protrej - peer doesn't talk CCP.
 */
static void ccp_protrej(ppp_pcb *pcb) {
  fsm *f = &pcb->ccp_fsm;
#if MPPE_SUPPORT
  ccp_options *go = &pcb->ccp_gotoptions;
#endif /* MPPE_SUPPORT */

  ccp_set(pcb, 0, 0, 0, 0);
  fsm_lowerdown(f);

#if MPPE_SUPPORT
  if (go->mppe) {
    ppp_error(("MPPE required but peer negotiation failed"));
    lcp_close(pcb, "MPPE required but peer negotiation failed");
  }
#endif /* MPPE_SUPPORT */
}

/*
 * ccp_resetci - initialize at start of negotiation.
 */
static void ccp_resetci(fsm *f) {
  ppp_pcb *pcb = f->pcb;
  ccp_options *go = &pcb->ccp_gotoptions;
  ccp_options *wo = &pcb->ccp_wantoptions;
#if MPPE_SUPPORT
  ccp_options *ao = &pcb->ccp_allowoptions;
#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT || BSDCOMPRESS_SUPPORT || PREDICTOR_SUPPORT
  u_char opt_buf[CCP_MAX_OPTION_LENGTH];
#endif /* DEFLATE_SUPPORT || BSDCOMPRESS_SUPPORT || PREDICTOR_SUPPORT */
#if DEFLATE_SUPPORT || BSDCOMPRESS_SUPPORT
  int res;
#endif /* DEFLATE_SUPPORT || BSDCOMPRESS_SUPPORT */

#if MPPE_SUPPORT
  if (pcb->settings.require_mppe) {
    wo->mppe = ao->mppe = (pcb->settings.refuse_mppe_40 ? 0 : MPPE_OPT_40) |
                          (pcb->settings.refuse_mppe_128 ? 0 : MPPE_OPT_128);
  }
#endif /* MPPE_SUPPORT */

  *go = *wo;
  pcb->ccp_all_rejected = 0;

#if MPPE_SUPPORT
  if (go->mppe) {
    int auth_mschap_bits = pcb->auth_done;
    int numbits;

    /*
     * Start with a basic sanity check: mschap[v2] auth must be in
     * exactly one direction.  RFC 3079 says that the keys are
     * 'derived from the credentials of the peer that initiated the call',
     * however the PPP protocol doesn't have such a concept, and pppd
     * cannot get this info externally.  Instead we do the best we can.
     * NB: If MPPE is required, all other compression opts are invalid.
     *     So, we return right away if we can't do it.
     */

    /* Leave only the mschap auth bits set */
    auth_mschap_bits &=
        (CHAP_MS_WITHPEER | CHAP_MS_PEER | CHAP_MS2_WITHPEER | CHAP_MS2_PEER);
    /* Count the mschap auths */
    auth_mschap_bits >>= CHAP_MS_SHIFT;
    numbits = 0;
    do {
      numbits += auth_mschap_bits & 1;
      auth_mschap_bits >>= 1;
    } while (auth_mschap_bits);
    if (numbits > 1) {
      ppp_error(("MPPE required, but auth done in both directions."));
      lcp_close(pcb, "MPPE required but not available");
      return;
    }
    if (!numbits) {
      ppp_error(("MPPE required, but MS-CHAP[v2] auth not performed."));
      lcp_close(pcb, "MPPE required but not available");
      return;
    }

    /* A plugin (eg radius) may not have obtained key material. */
    if (!pcb->mppe_keys_set) {
      ppp_error(("MPPE required, but keys are not available.  "
                 "Possible plugin problem?"));
      lcp_close(pcb, "MPPE required but not available");
      return;
    }

    /* LM auth not supported for MPPE */
    if (pcb->auth_done & (CHAP_MS_WITHPEER | CHAP_MS_PEER)) {
      /* This might be noise */
      if (go->mppe & MPPE_OPT_40) {
        ppp_notice(("Disabling 40-bit MPPE; MS-CHAP LM not supported"));
        go->mppe &= ~MPPE_OPT_40;
        wo->mppe &= ~MPPE_OPT_40;
      }
    }

    /* Last check: can we actually negotiate something? */
    if (!(go->mppe & (MPPE_OPT_40 | MPPE_OPT_128))) {
      /* Could be misconfig, could be 40-bit disabled above. */
      ppp_error(("MPPE required, but both 40-bit and 128-bit disabled."));
      lcp_close(pcb, "MPPE required but not available");
      return;
    }

    /* sync options */
    ao->mppe = go->mppe;
    /* MPPE is not compatible with other compression types */
#if BSDCOMPRESS_SUPPORT
    ao->bsd_compress = go->bsd_compress = 0;
#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT
    ao->predictor_1 = go->predictor_1 = 0;
    ao->predictor_2 = go->predictor_2 = 0;
#endif /* PREDICTOR_SUPPORT */
#if DEFLATE_SUPPORT
    ao->deflate = go->deflate = 0;
#endif /* DEFLATE_SUPPORT */
  }
#endif /* MPPE_SUPPORT */

  /*
   * Check whether the kernel knows about the various
   * compression methods we might request.
   */
#if BSDCOMPRESS_SUPPORT
  /* FIXME: we don't need to test if BSD compress is available
   * if BSDCOMPRESS_SUPPORT is set, it is.
   */
  if (go->bsd_compress) {
    opt_buf[0] = CI_BSD_COMPRESS;
    opt_buf[1] = CILEN_BSD_COMPRESS;
    for (;;) {
      if (go->bsd_bits < BSD_MIN_BITS) {
        go->bsd_compress = 0;
        break;
      }
      opt_buf[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, go->bsd_bits);
      res = ccp_test(pcb, opt_buf, CILEN_BSD_COMPRESS, 0);
      if (res > 0) {
        break;
      } else if (res < 0) {
        go->bsd_compress = 0;
        break;
      }
      go->bsd_bits--;
    }
  }
#endif /* BSDCOMPRESS_SUPPORT */
#if DEFLATE_SUPPORT
  /* FIXME: we don't need to test if deflate is available
   * if DEFLATE_SUPPORT is set, it is.
   */
  if (go->deflate) {
    if (go->deflate_correct) {
      opt_buf[0] = CI_DEFLATE;
      opt_buf[1] = CILEN_DEFLATE;
      opt_buf[3] = DEFLATE_CHK_SEQUENCE;
      for (;;) {
        if (go->deflate_size < DEFLATE_MIN_WORKS) {
          go->deflate_correct = 0;
          break;
        }
        opt_buf[2] = DEFLATE_MAKE_OPT(go->deflate_size);
        res = ccp_test(pcb, opt_buf, CILEN_DEFLATE, 0);
        if (res > 0) {
          break;
        } else if (res < 0) {
          go->deflate_correct = 0;
          break;
        }
        go->deflate_size--;
      }
    }
    if (go->deflate_draft) {
      opt_buf[0] = CI_DEFLATE_DRAFT;
      opt_buf[1] = CILEN_DEFLATE;
      opt_buf[3] = DEFLATE_CHK_SEQUENCE;
      for (;;) {
        if (go->deflate_size < DEFLATE_MIN_WORKS) {
          go->deflate_draft = 0;
          break;
        }
        opt_buf[2] = DEFLATE_MAKE_OPT(go->deflate_size);
        res = ccp_test(pcb, opt_buf, CILEN_DEFLATE, 0);
        if (res > 0) {
          break;
        } else if (res < 0) {
          go->deflate_draft = 0;
          break;
        }
        go->deflate_size--;
      }
    }
    if (!go->deflate_correct && !go->deflate_draft)
      go->deflate = 0;
  }
#endif /* DEFLATE_SUPPORT */
#if PREDICTOR_SUPPORT
  /* FIXME: we don't need to test if predictor is available,
   * if PREDICTOR_SUPPORT is set, it is.
   */
  if (go->predictor_1) {
    opt_buf[0] = CI_PREDICTOR_1;
    opt_buf[1] = CILEN_PREDICTOR_1;
    if (ccp_test(pcb, opt_buf, CILEN_PREDICTOR_1, 0) <= 0)
      go->predictor_1 = 0;
  }
  if (go->predictor_2) {
    opt_buf[0] = CI_PREDICTOR_2;
    opt_buf[1] = CILEN_PREDICTOR_2;
    if (ccp_test(pcb, opt_buf, CILEN_PREDICTOR_2, 0) <= 0)
      go->predictor_2 = 0;
  }
#endif /* PREDICTOR_SUPPORT */
}

/*
 * ccp_cilen - Return total length of our configuration info.
 */
static int ccp_cilen(fsm *f) {
  ppp_pcb *pcb = f->pcb;
  ccp_options *go = &pcb->ccp_gotoptions;

  return 0
#if BSDCOMPRESS_SUPPORT
         + (go->bsd_compress ? CILEN_BSD_COMPRESS : 0)
#endif /* BSDCOMPRESS_SUPPORT */
#if DEFLATE_SUPPORT
         + (go->deflate && go->deflate_correct ? CILEN_DEFLATE : 0) +
         (go->deflate && go->deflate_draft ? CILEN_DEFLATE : 0)
#endif /* DEFLATE_SUPPORT */
#if PREDICTOR_SUPPORT
         + (go->predictor_1 ? CILEN_PREDICTOR_1 : 0) +
         (go->predictor_2 ? CILEN_PREDICTOR_2 : 0)
#endif /* PREDICTOR_SUPPORT */
#if MPPE_SUPPORT
         + (go->mppe ? CILEN_MPPE : 0)
#endif /* MPPE_SUPPORT */
      ;
}

/*
 * ccp_addci - put our requests in a packet.
 */
static void ccp_addci(fsm *f, u_char *p, int *lenp) {
  ppp_pcb *pcb = f->pcb;
  ccp_options *go = &pcb->ccp_gotoptions;
  u_char *p0 = p;

  /*
   * Add the compression types that we can receive, in decreasing
   * preference order.
   */
#if MPPE_SUPPORT
  if (go->mppe) {
    p[0] = CI_MPPE;
    p[1] = CILEN_MPPE;
    MPPE_OPTS_TO_CI(go->mppe, &p[2]);
    mppe_init(pcb, &pcb->mppe_decomp, go->mppe);
    p += CILEN_MPPE;
  }
#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT
  if (go->deflate) {
    if (go->deflate_correct) {
      p[0] = CI_DEFLATE;
      p[1] = CILEN_DEFLATE;
      p[2] = DEFLATE_MAKE_OPT(go->deflate_size);
      p[3] = DEFLATE_CHK_SEQUENCE;
      p += CILEN_DEFLATE;
    }
    if (go->deflate_draft) {
      p[0] = CI_DEFLATE_DRAFT;
      p[1] = CILEN_DEFLATE;
      p[2] = p[2 - CILEN_DEFLATE];
      p[3] = DEFLATE_CHK_SEQUENCE;
      p += CILEN_DEFLATE;
    }
  }
#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT
  if (go->bsd_compress) {
    p[0] = CI_BSD_COMPRESS;
    p[1] = CILEN_BSD_COMPRESS;
    p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, go->bsd_bits);
    p += CILEN_BSD_COMPRESS;
  }
#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT
  /* XXX Should Predictor 2 be preferable to Predictor 1? */
  if (go->predictor_1) {
    p[0] = CI_PREDICTOR_1;
    p[1] = CILEN_PREDICTOR_1;
    p += CILEN_PREDICTOR_1;
  }
  if (go->predictor_2) {
    p[0] = CI_PREDICTOR_2;
    p[1] = CILEN_PREDICTOR_2;
    p += CILEN_PREDICTOR_2;
  }
#endif /* PREDICTOR_SUPPORT */

  go->method = (p > p0) ? p0[0] : 0;

  *lenp = p - p0;
}

/*
 * ccp_ackci - process a received configure-ack, and return
 * 1 iff the packet was OK.
 */
static int ccp_ackci(fsm *f, u_char *p, int len) {
  ppp_pcb *pcb = f->pcb;
  ccp_options *go = &pcb->ccp_gotoptions;
#if BSDCOMPRESS_SUPPORT || PREDICTOR_SUPPORT
  u_char *p0 = p;
#endif /* BSDCOMPRESS_SUPPORT || PREDICTOR_SUPPORT */

#if MPPE_SUPPORT
  if (go->mppe) {
    u_char opt_buf[CILEN_MPPE];

    opt_buf[0] = CI_MPPE;
    opt_buf[1] = CILEN_MPPE;
    MPPE_OPTS_TO_CI(go->mppe, &opt_buf[2]);
    if (len < CILEN_MPPE || memcmp(opt_buf, p, CILEN_MPPE))
      return 0;
    p += CILEN_MPPE;
    len -= CILEN_MPPE;
    /* XXX Cope with first/fast ack */
    if (len == 0)
      return 1;
  }
#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT
  if (go->deflate) {
    if (len < CILEN_DEFLATE ||
        p[0] != (go->deflate_correct ? CI_DEFLATE : CI_DEFLATE_DRAFT) ||
        p[1] != CILEN_DEFLATE || p[2] != DEFLATE_MAKE_OPT(go->deflate_size) ||
        p[3] != DEFLATE_CHK_SEQUENCE)
      return 0;
    p += CILEN_DEFLATE;
    len -= CILEN_DEFLATE;
    /* XXX Cope with first/fast ack */
    if (len == 0)
      return 1;
    if (go->deflate_correct && go->deflate_draft) {
      if (len < CILEN_DEFLATE || p[0] != CI_DEFLATE_DRAFT ||
          p[1] != CILEN_DEFLATE || p[2] != DEFLATE_MAKE_OPT(go->deflate_size) ||
          p[3] != DEFLATE_CHK_SEQUENCE)
        return 0;
      p += CILEN_DEFLATE;
      len -= CILEN_DEFLATE;
    }
  }
#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT
  if (go->bsd_compress) {
    if (len < CILEN_BSD_COMPRESS || p[0] != CI_BSD_COMPRESS ||
        p[1] != CILEN_BSD_COMPRESS ||
        p[2] != BSD_MAKE_OPT(BSD_CURRENT_VERSION, go->bsd_bits))
      return 0;
    p += CILEN_BSD_COMPRESS;
    len -= CILEN_BSD_COMPRESS;
    /* XXX Cope with first/fast ack */
    if (p == p0 && len == 0)
      return 1;
  }
#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT
  if (go->predictor_1) {
    if (len < CILEN_PREDICTOR_1 || p[0] != CI_PREDICTOR_1 ||
        p[1] != CILEN_PREDICTOR_1)
      return 0;
    p += CILEN_PREDICTOR_1;
    len -= CILEN_PREDICTOR_1;
    /* XXX Cope with first/fast ack */
    if (p == p0 && len == 0)
      return 1;
  }
  if (go->predictor_2) {
    if (len < CILEN_PREDICTOR_2 || p[0] != CI_PREDICTOR_2 ||
        p[1] != CILEN_PREDICTOR_2)
      return 0;
    p += CILEN_PREDICTOR_2;
    len -= CILEN_PREDICTOR_2;
    /* XXX Cope with first/fast ack */
    if (p == p0 && len == 0)
      return 1;
  }
#endif /* PREDICTOR_SUPPORT */

  if (len != 0)
    return 0;
  return 1;
}

/*
 * ccp_nakci - process received configure-nak.
 * Returns 1 iff the nak was OK.
 */
static int ccp_nakci(fsm *f, u_char *p, int len, int treat_as_reject) {
  ppp_pcb *pcb = f->pcb;
  ccp_options *go = &pcb->ccp_gotoptions;
  ccp_options no;   /* options we've seen already */
  ccp_options try_; /* options to ask for next time */
  LWIP_UNUSED_ARG(treat_as_reject);
#if !MPPE_SUPPORT && !DEFLATE_SUPPORT && !BSDCOMPRESS_SUPPORT
  LWIP_UNUSED_ARG(p);
  LWIP_UNUSED_ARG(len);
#endif /* !MPPE_SUPPORT && !DEFLATE_SUPPORT && !BSDCOMPRESS_SUPPORT */

  memset(&no, 0, sizeof(no));
  try_ = *go;

#if MPPE_SUPPORT
  if (go->mppe && len >= CILEN_MPPE && p[0] == CI_MPPE && p[1] == CILEN_MPPE) {
    no.mppe = 1;
    /*
     * Peer wants us to use a different strength or other setting.
     * Fail if we aren't willing to use his suggestion.
     */
    MPPE_CI_TO_OPTS(&p[2], try_.mppe);
    if ((try_.mppe & MPPE_OPT_STATEFUL) && pcb->settings.refuse_mppe_stateful) {
      ppp_error(("Refusing MPPE stateful mode offered by peer"));
      try_.mppe = 0;
    } else if (((go->mppe | MPPE_OPT_STATEFUL) & try_.mppe) != try_.mppe) {
      /* Peer must have set options we didn't request (suggest) */
      try_.mppe = 0;
    }

    if (!try_.mppe) {
      ppp_error(("MPPE required but peer negotiation failed"));
      lcp_close(pcb, "MPPE required but peer negotiation failed");
    }
  }
#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT
  if (go->deflate && len >= CILEN_DEFLATE &&
      p[0] == (go->deflate_correct ? CI_DEFLATE : CI_DEFLATE_DRAFT) &&
      p[1] == CILEN_DEFLATE) {
    no.deflate = 1;
    /*
     * Peer wants us to use a different code size or something.
     * Stop asking for Deflate if we don't understand his suggestion.
     */
    if (DEFLATE_METHOD(p[2]) != DEFLATE_METHOD_VAL ||
        DEFLATE_SIZE(p[2]) < DEFLATE_MIN_WORKS || p[3] != DEFLATE_CHK_SEQUENCE)
      try_.deflate = 0;
    else if (DEFLATE_SIZE(p[2]) < go->deflate_size)
      try_.deflate_size = DEFLATE_SIZE(p[2]);
    p += CILEN_DEFLATE;
    len -= CILEN_DEFLATE;
    if (go->deflate_correct && go->deflate_draft && len >= CILEN_DEFLATE &&
        p[0] == CI_DEFLATE_DRAFT && p[1] == CILEN_DEFLATE) {
      p += CILEN_DEFLATE;
      len -= CILEN_DEFLATE;
    }
  }
#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT
  if (go->bsd_compress && len >= CILEN_BSD_COMPRESS &&
      p[0] == CI_BSD_COMPRESS && p[1] == CILEN_BSD_COMPRESS) {
    no.bsd_compress = 1;
    /*
     * Peer wants us to use a different number of bits
     * or a different version.
     */
    if (BSD_VERSION(p[2]) != BSD_CURRENT_VERSION)
      try_.bsd_compress = 0;
    else if (BSD_NBITS(p[2]) < go->bsd_bits)
      try_.bsd_bits = BSD_NBITS(p[2]);
    p += CILEN_BSD_COMPRESS;
    len -= CILEN_BSD_COMPRESS;
  }
#endif /* BSDCOMPRESS_SUPPORT */

  /*
   * Predictor-1 and 2 have no options, so they can't be Naked.
   *
   * There may be remaining options but we ignore them.
   */

  if (f->state != PPP_FSM_OPENED)
    *go = try_;
  return 1;
}

/*
 * ccp_rejci - reject some of our suggested compression methods.
 */
static int ccp_rejci(fsm *f, u_char *p, int len) {
  ppp_pcb *pcb = f->pcb;
  ccp_options *go = &pcb->ccp_gotoptions;
  ccp_options try_; /* options to request next time */

  try_ = *go;

  /*
   * Cope with empty configure-rejects by ceasing to send
   * configure-requests.
   */
  if (len == 0 && pcb->ccp_all_rejected)
    return -1;

#if MPPE_SUPPORT
  if (go->mppe && len >= CILEN_MPPE && p[0] == CI_MPPE && p[1] == CILEN_MPPE) {
    ppp_error(("MPPE required but peer refused"));
    lcp_close(pcb, "MPPE required but peer refused");
    p += CILEN_MPPE;
    len -= CILEN_MPPE;
  }
#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT
  if (go->deflate_correct && len >= CILEN_DEFLATE && p[0] == CI_DEFLATE &&
      p[1] == CILEN_DEFLATE) {
    if (p[2] != DEFLATE_MAKE_OPT(go->deflate_size) ||
        p[3] != DEFLATE_CHK_SEQUENCE)
      return 0; /* Rej is bad */
    try_.deflate_correct = 0;
    p += CILEN_DEFLATE;
    len -= CILEN_DEFLATE;
  }
  if (go->deflate_draft && len >= CILEN_DEFLATE && p[0] == CI_DEFLATE_DRAFT &&
      p[1] == CILEN_DEFLATE) {
    if (p[2] != DEFLATE_MAKE_OPT(go->deflate_size) ||
        p[3] != DEFLATE_CHK_SEQUENCE)
      return 0; /* Rej is bad */
    try_.deflate_draft = 0;
    p += CILEN_DEFLATE;
    len -= CILEN_DEFLATE;
  }
  if (!try_.deflate_correct && !try_.deflate_draft)
    try_.deflate = 0;
#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT
  if (go->bsd_compress && len >= CILEN_BSD_COMPRESS &&
      p[0] == CI_BSD_COMPRESS && p[1] == CILEN_BSD_COMPRESS) {
    if (p[2] != BSD_MAKE_OPT(BSD_CURRENT_VERSION, go->bsd_bits))
      return 0;
    try_.bsd_compress = 0;
    p += CILEN_BSD_COMPRESS;
    len -= CILEN_BSD_COMPRESS;
  }
#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT
  if (go->predictor_1 && len >= CILEN_PREDICTOR_1 && p[0] == CI_PREDICTOR_1 &&
      p[1] == CILEN_PREDICTOR_1) {
    try_.predictor_1 = 0;
    p += CILEN_PREDICTOR_1;
    len -= CILEN_PREDICTOR_1;
  }
  if (go->predictor_2 && len >= CILEN_PREDICTOR_2 && p[0] == CI_PREDICTOR_2 &&
      p[1] == CILEN_PREDICTOR_2) {
    try_.predictor_2 = 0;
    p += CILEN_PREDICTOR_2;
    len -= CILEN_PREDICTOR_2;
  }
#endif /* PREDICTOR_SUPPORT */

  if (len != 0)
    return 0;

  if (f->state != PPP_FSM_OPENED)
    *go = try_;

  return 1;
}

/*
 * ccp_reqci - processed a received configure-request.
 * Returns CONFACK, CONFNAK or CONFREJ and the packet modified
 * appropriately.
 */
static int ccp_reqci(fsm *f, u_char *p, int *lenp, int dont_nak) {
  ppp_pcb *pcb = f->pcb;
  ccp_options *ho = &pcb->ccp_hisoptions;
  ccp_options *ao = &pcb->ccp_allowoptions;
  int ret, newret;
#if DEFLATE_SUPPORT || BSDCOMPRESS_SUPPORT
  int res;
  int nb;
#endif /* DEFLATE_SUPPORT || BSDCOMPRESS_SUPPORT */
  u_char *p0, *retp;
  int len, clen, type;
#if MPPE_SUPPORT
  u8_t rej_for_ci_mppe = 1; /* Are we rejecting based on a bad/missing */
                            /* CI_MPPE, or due to other options?       */
#endif                      /* MPPE_SUPPORT */

  ret = CONFACK;
  retp = p0 = p;
  len = *lenp;

  memset(ho, 0, sizeof(ccp_options));
  ho->method = (len > 0) ? p[0] : 0;

  while (len > 0) {
    newret = CONFACK;
    if (len < 2 || p[1] < 2 || p[1] > len) {
      /* length is bad */
      clen = len;
      newret = CONFREJ;

    } else {
      type = p[0];
      clen = p[1];

      switch (type) {
#if MPPE_SUPPORT
      case CI_MPPE:
        if (!ao->mppe || clen != CILEN_MPPE) {
          newret = CONFREJ;
          break;
        }
        MPPE_CI_TO_OPTS(&p[2], ho->mppe);

        /* Nak if anything unsupported or unknown are set. */
        if (ho->mppe & MPPE_OPT_UNSUPPORTED) {
          newret = CONFNAK;
          ho->mppe &= ~MPPE_OPT_UNSUPPORTED;
        }
        if (ho->mppe & MPPE_OPT_UNKNOWN) {
          newret = CONFNAK;
          ho->mppe &= ~MPPE_OPT_UNKNOWN;
        }

        /* Check state opt */
        if (ho->mppe & MPPE_OPT_STATEFUL) {
          /*
           * We can Nak and request stateless, but it's a
           * lot easier to just assume the peer will request
           * it if he can do it; stateful mode is bad over
           * the Internet -- which is where we expect MPPE.
           */
          if (pcb->settings.refuse_mppe_stateful) {
            ppp_error(("Refusing MPPE stateful mode offered by peer"));
            newret = CONFREJ;
            break;
          }
        }

        /* Find out which of {S,L} are set. */
        if ((ho->mppe & MPPE_OPT_128) && (ho->mppe & MPPE_OPT_40)) {
          /* Both are set, negotiate the strongest. */
          newret = CONFNAK;
          if (ao->mppe & MPPE_OPT_128)
            ho->mppe &= ~MPPE_OPT_40;
          else if (ao->mppe & MPPE_OPT_40)
            ho->mppe &= ~MPPE_OPT_128;
          else {
            newret = CONFREJ;
            break;
          }
        } else if (ho->mppe & MPPE_OPT_128) {
          if (!(ao->mppe & MPPE_OPT_128)) {
            newret = CONFREJ;
            break;
          }
        } else if (ho->mppe & MPPE_OPT_40) {
          if (!(ao->mppe & MPPE_OPT_40)) {
            newret = CONFREJ;
            break;
          }
        } else {
          /* Neither are set. */
          /* We cannot accept this.  */
          newret = CONFNAK;
          /* Give the peer our idea of what can be used,
             so it can choose and confirm */
          ho->mppe = ao->mppe;
        }

        /* rebuild the opts */
        MPPE_OPTS_TO_CI(ho->mppe, &p[2]);
        if (newret == CONFACK) {
          int mtu;

          mppe_init(pcb, &pcb->mppe_comp, ho->mppe);
          /*
           * We need to decrease the interface MTU by MPPE_PAD
           * because MPPE frames **grow**.  The kernel [must]
           * allocate MPPE_PAD extra bytes in xmit buffers.
           */
          mtu = ppp_netif_get_mtu(pcb);
          if (mtu)
            ppp_netif_set_mtu(pcb, mtu - MPPE_PAD);
          else
            newret = CONFREJ;
        }

        /*
         * We have accepted MPPE or are willing to negotiate
         * MPPE parameters.  A CONFREJ is due to subsequent
         * (non-MPPE) processing.
         */
        rej_for_ci_mppe = 0;
        break;
#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT
      case CI_DEFLATE:
      case CI_DEFLATE_DRAFT:
        if (!ao->deflate || clen != CILEN_DEFLATE ||
            (!ao->deflate_correct && type == CI_DEFLATE) ||
            (!ao->deflate_draft && type == CI_DEFLATE_DRAFT)) {
          newret = CONFREJ;
          break;
        }

        ho->deflate = 1;
        ho->deflate_size = nb = DEFLATE_SIZE(p[2]);
        if (DEFLATE_METHOD(p[2]) != DEFLATE_METHOD_VAL ||
            p[3] != DEFLATE_CHK_SEQUENCE || nb > ao->deflate_size ||
            nb < DEFLATE_MIN_WORKS) {
          newret = CONFNAK;
          if (!dont_nak) {
            p[2] = DEFLATE_MAKE_OPT(ao->deflate_size);
            p[3] = DEFLATE_CHK_SEQUENCE;
            /* fall through to test this #bits below */
          } else
            break;
        }

        /*
         * Check whether we can do Deflate with the window
         * size they want.  If the window is too big, reduce
         * it until the kernel can cope and nak with that.
         * We only check this for the first option.
         */
        if (p == p0) {
          for (;;) {
            res = ccp_test(pcb, p, CILEN_DEFLATE, 1);
            if (res > 0)
              break; /* it's OK now */
            if (res < 0 || nb == DEFLATE_MIN_WORKS || dont_nak) {
              newret = CONFREJ;
              p[2] = DEFLATE_MAKE_OPT(ho->deflate_size);
              break;
            }
            newret = CONFNAK;
            --nb;
            p[2] = DEFLATE_MAKE_OPT(nb);
          }
        }
        break;
#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT
      case CI_BSD_COMPRESS:
        if (!ao->bsd_compress || clen != CILEN_BSD_COMPRESS) {
          newret = CONFREJ;
          break;
        }

        ho->bsd_compress = 1;
        ho->bsd_bits = nb = BSD_NBITS(p[2]);
        if (BSD_VERSION(p[2]) != BSD_CURRENT_VERSION || nb > ao->bsd_bits ||
            nb < BSD_MIN_BITS) {
          newret = CONFNAK;
          if (!dont_nak) {
            p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, ao->bsd_bits);
            /* fall through to test this #bits below */
          } else
            break;
        }

        /*
         * Check whether we can do BSD-Compress with the code
         * size they want.  If the code size is too big, reduce
         * it until the kernel can cope and nak with that.
         * We only check this for the first option.
         */
        if (p == p0) {
          for (;;) {
            res = ccp_test(pcb, p, CILEN_BSD_COMPRESS, 1);
            if (res > 0)
              break;
            if (res < 0 || nb == BSD_MIN_BITS || dont_nak) {
              newret = CONFREJ;
              p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, ho->bsd_bits);
              break;
            }
            newret = CONFNAK;
            --nb;
            p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, nb);
          }
        }
        break;
#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT
      case CI_PREDICTOR_1:
        if (!ao->predictor_1 || clen != CILEN_PREDICTOR_1) {
          newret = CONFREJ;
          break;
        }

        ho->predictor_1 = 1;
        if (p == p0 && ccp_test(pcb, p, CILEN_PREDICTOR_1, 1) <= 0) {
          newret = CONFREJ;
        }
        break;

      case CI_PREDICTOR_2:
        if (!ao->predictor_2 || clen != CILEN_PREDICTOR_2) {
          newret = CONFREJ;
          break;
        }

        ho->predictor_2 = 1;
        if (p == p0 && ccp_test(pcb, p, CILEN_PREDICTOR_2, 1) <= 0) {
          newret = CONFREJ;
        }
        break;
#endif /* PREDICTOR_SUPPORT */

      default:
        newret = CONFREJ;
      }
    }

    if (newret == CONFNAK && dont_nak)
      newret = CONFREJ;
    if (!(newret == CONFACK || (newret == CONFNAK && ret == CONFREJ))) {
      /* we're returning this option */
      if (newret == CONFREJ && ret == CONFNAK)
        retp = p0;
      ret = newret;
      if (p != retp)
        MEMCPY(retp, p, clen);
      retp += clen;
    }

    p += clen;
    len -= clen;
  }

  if (ret != CONFACK) {
    if (ret == CONFREJ && *lenp == retp - p0)
      pcb->ccp_all_rejected = 1;
    else
      *lenp = retp - p0;
  }
#if MPPE_SUPPORT
  if (ret == CONFREJ && ao->mppe && rej_for_ci_mppe) {
    ppp_error(("MPPE required but peer negotiation failed"));
    lcp_close(pcb, "MPPE required but peer negotiation failed");
  }
#endif /* MPPE_SUPPORT */
  return ret;
}

/*
 * Make a string name for a compression method (or 2).
 */
static const char *method_name(ccp_options *opt, ccp_options *opt2) {
  static char result[64];
#if !DEFLATE_SUPPORT && !BSDCOMPRESS_SUPPORT
  LWIP_UNUSED_ARG(opt2);
#endif /* !DEFLATE_SUPPORT && !BSDCOMPRESS_SUPPORT */

  if (!ccp_anycompress(opt))
    return "(none)";
  switch (opt->method) {
#if MPPE_SUPPORT
  case CI_MPPE: {
    char *p = result;
    char *q = result + sizeof(result); /* 1 past result */

    ppp_slprintf(p, q - p, "MPPE ");
    p += 5;
    if (opt->mppe & MPPE_OPT_128) {
      ppp_slprintf(p, q - p, "128-bit ");
      p += 8;
    }
    if (opt->mppe & MPPE_OPT_40) {
      ppp_slprintf(p, q - p, "40-bit ");
      p += 7;
    }
    if (opt->mppe & MPPE_OPT_STATEFUL)
      ppp_slprintf(p, q - p, "stateful");
    else
      ppp_slprintf(p, q - p, "stateless");

    break;
  }
#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT
  case CI_DEFLATE:
  case CI_DEFLATE_DRAFT:
    if (opt2 != NULL && opt2->deflate_size != opt->deflate_size)
      ppp_slprintf(result, sizeof(result), "Deflate%s (%d/%d)",
                   (opt->method == CI_DEFLATE_DRAFT ? "(old#)" : ""),
                   opt->deflate_size, opt2->deflate_size);
    else
      ppp_slprintf(result, sizeof(result), "Deflate%s (%d)",
                   (opt->method == CI_DEFLATE_DRAFT ? "(old#)" : ""),
                   opt->deflate_size);
    break;
#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT
  case CI_BSD_COMPRESS:
    if (opt2 != NULL && opt2->bsd_bits != opt->bsd_bits)
      ppp_slprintf(result, sizeof(result), "BSD-Compress (%d/%d)",
                   opt->bsd_bits, opt2->bsd_bits);
    else
      ppp_slprintf(result, sizeof(result), "BSD-Compress (%d)", opt->bsd_bits);
    break;
#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT
  case CI_PREDICTOR_1:
    return "Predictor 1";
  case CI_PREDICTOR_2:
    return "Predictor 2";
#endif /* PREDICTOR_SUPPORT */
  default:
    ppp_slprintf(result, sizeof(result), "Method %d", opt->method);
  }
  return result;
}

/*
 * CCP has come up - inform the kernel driver and log a message.
 */
static void ccp_up(fsm *f) {
  ppp_pcb *pcb = f->pcb;
  ccp_options *go = &pcb->ccp_gotoptions;
  ccp_options *ho = &pcb->ccp_hisoptions;
  char method1[64];

  ccp_set(pcb, 1, 1, go->method, ho->method);
  if (ccp_anycompress(go)) {
    if (ccp_anycompress(ho)) {
      if (go->method == ho->method) {
        ppp_notice(("%s compression enabled", method_name(go, ho)));
      } else {
        ppp_strlcpy(method1, method_name(go, NULL), sizeof(method1));
        ppp_notice(
            ("%s / %s compression enabled", method1, method_name(ho, NULL)));
      }
    } else
      ppp_notice(("%s receive compression enabled", method_name(go, NULL)));
  } else if (ccp_anycompress(ho))
    ppp_notice(("%s transmit compression enabled", method_name(ho, NULL)));
#if MPPE_SUPPORT
  if (go->mppe) {
    continue_networks(pcb); /* Bring up IP et al */
  }
#endif /* MPPE_SUPPORT */
}

/*
 * CCP has gone down - inform the kernel driver.
 */
static void ccp_down(fsm *f) {
  ppp_pcb *pcb = f->pcb;
#if MPPE_SUPPORT
  ccp_options *go = &pcb->ccp_gotoptions;
#endif /* MPPE_SUPPORT */

  if (pcb->ccp_localstate & RACK_PENDING)
    UNTIMEOUT(ccp_rack_timeout, f);
  pcb->ccp_localstate = 0;
  ccp_set(pcb, 1, 0, 0, 0);
#if MPPE_SUPPORT
  if (go->mppe) {
    go->mppe = 0;
    if (pcb->lcp_fsm.state == PPP_FSM_OPENED) {
      /* If LCP is not already going down, make sure it does. */
      ppp_error(("MPPE disabled"));
      lcp_close(pcb, "MPPE disabled");
    }
  }
#endif /* MPPE_SUPPORT */
}

#if PRINTPKT_SUPPORT
/*
 * Print the contents of a CCP packet.
 */
static const char *const ccp_codenames[] = {
    "ConfReq", "ConfAck", "ConfNak", "ConfRej",  "TermReq",
    "TermAck", "CodeRej", NULL,      NULL,       NULL,
    NULL,      NULL,      NULL,      "ResetReq", "ResetAck",
};

static int ccp_printpkt(const u_char *p, int plen,
                        void (*printer)(void *, const char *, ...), void *arg) {
  const u_char *p0, *optend;
  int code, id, len;
  int optlen;

  p0 = p;
  if (plen < HEADERLEN)
    return 0;
  code = p[0];
  id = p[1];
  len = (p[2] << 8) + p[3];
  if (len < HEADERLEN || len > plen)
    return 0;

  if (code >= 1 && code <= (int)LWIP_ARRAYSIZE(ccp_codenames) &&
      ccp_codenames[code - 1] != NULL)
    printer(arg, " %s", ccp_codenames[code - 1]);
  else
    printer(arg, " code=0x%x", code);
  printer(arg, " id=0x%x", id);
  len -= HEADERLEN;
  p += HEADERLEN;

  switch (code) {
  case CONFREQ:
  case CONFACK:
  case CONFNAK:
  case CONFREJ:
    /* print list of possible compression methods */
    while (len >= 2) {
      code = p[0];
      optlen = p[1];
      if (optlen < 2 || optlen > len)
        break;
      printer(arg, " <");
      len -= optlen;
      optend = p + optlen;
      switch (code) {
#if MPPE_SUPPORT
      case CI_MPPE:
        if (optlen >= CILEN_MPPE) {
          u_char mppe_opts;

          MPPE_CI_TO_OPTS(&p[2], mppe_opts);
          printer(arg, "mppe %s %s %s %s %s %s%s",
                  (p[2] & MPPE_H_BIT) ? "+H" : "-H",
                  (p[5] & MPPE_M_BIT) ? "+M" : "-M",
                  (p[5] & MPPE_S_BIT) ? "+S" : "-S",
                  (p[5] & MPPE_L_BIT) ? "+L" : "-L",
                  (p[5] & MPPE_D_BIT) ? "+D" : "-D",
                  (p[5] & MPPE_C_BIT) ? "+C" : "-C",
                  (mppe_opts & MPPE_OPT_UNKNOWN) ? " +U" : "");
          if (mppe_opts & MPPE_OPT_UNKNOWN)
            printer(arg, " (%.2x %.2x %.2x %.2x)", p[2], p[3], p[4], p[5]);
          p += CILEN_MPPE;
        }
        break;
#endif /* MPPE_SUPPORT */
#if DEFLATE_SUPPORT
      case CI_DEFLATE:
      case CI_DEFLATE_DRAFT:
        if (optlen >= CILEN_DEFLATE) {
          printer(arg, "deflate%s %d",
                  (code == CI_DEFLATE_DRAFT ? "(old#)" : ""),
                  DEFLATE_SIZE(p[2]));
          if (DEFLATE_METHOD(p[2]) != DEFLATE_METHOD_VAL)
            printer(arg, " method %d", DEFLATE_METHOD(p[2]));
          if (p[3] != DEFLATE_CHK_SEQUENCE)
            printer(arg, " check %d", p[3]);
          p += CILEN_DEFLATE;
        }
        break;
#endif /* DEFLATE_SUPPORT */
#if BSDCOMPRESS_SUPPORT
      case CI_BSD_COMPRESS:
        if (optlen >= CILEN_BSD_COMPRESS) {
          printer(arg, "bsd v%d %d", BSD_VERSION(p[2]), BSD_NBITS(p[2]));
          p += CILEN_BSD_COMPRESS;
        }
        break;
#endif /* BSDCOMPRESS_SUPPORT */
#if PREDICTOR_SUPPORT
      case CI_PREDICTOR_1:
        if (optlen >= CILEN_PREDICTOR_1) {
          printer(arg, "predictor 1");
          p += CILEN_PREDICTOR_1;
        }
        break;
      case CI_PREDICTOR_2:
        if (optlen >= CILEN_PREDICTOR_2) {
          printer(arg, "predictor 2");
          p += CILEN_PREDICTOR_2;
        }
        break;
#endif /* PREDICTOR_SUPPORT */
      default:
        break;
      }
      while (p < optend)
        printer(arg, " %.2x", *p++);
      printer(arg, ">");
    }
    break;

  case TERMACK:
  case TERMREQ:
    if (len > 0 && *p >= ' ' && *p < 0x7f) {
      ppp_print_string(p, len, printer, arg);
      p += len;
      len = 0;
    }
    break;
  default:
    break;
  }

  /* dump out the rest of the packet in hex */
  while (--len >= 0)
    printer(arg, " %.2x", *p++);

  return p - p0;
}
#endif /* PRINTPKT_SUPPORT */

#if PPP_DATAINPUT
/*
 * We have received a packet that the decompressor failed to
 * decompress.  Here we would expect to issue a reset-request, but
 * Motorola has a patent on resetting the compressor as a result of
 * detecting an error in the decompressed data after decompression.
 * (See US patent 5,130,993; international patent publication number
 * WO 91/10289; Australian patent 73296/91.)
 *
 * So we ask the kernel whether the error was detected after
 * decompression; if it was, we take CCP down, thus disabling
 * compression :-(, otherwise we issue the reset-request.
 */
static void ccp_datainput(ppp_pcb *pcb, u_char *pkt, int len) {
  fsm *f;
#if MPPE_SUPPORT
  ccp_options *go = &pcb->ccp_gotoptions;
#endif /* MPPE_SUPPORT */
  LWIP_UNUSED_ARG(pkt);
  LWIP_UNUSED_ARG(len);

  f = &pcb->ccp_fsm;
  if (f->state == PPP_FSM_OPENED) {
    if (ccp_fatal_error(pcb)) {
      /*
       * Disable compression by taking CCP down.
       */
      ppp_error(("Lost compression sync: disabling compression"));
      ccp_close(pcb, "Lost compression sync");
#if MPPE_SUPPORT
      /*
       * If we were doing MPPE, we must also take the link down.
       */
      if (go->mppe) {
        ppp_error(("Too many MPPE errors, closing LCP"));
        lcp_close(pcb, "Too many MPPE errors");
      }
#endif /* MPPE_SUPPORT */
    } else {
      /*
       * Send a reset-request to reset the peer's compressor.
       * We don't do that if we are still waiting for an
       * acknowledgement to a previous reset-request.
       */
      if (!(pcb->ccp_localstate & RACK_PENDING)) {
        fsm_sdata(f, CCP_RESETREQ, f->reqid = ++f->id, NULL, 0);
        TIMEOUT(ccp_rack_timeout, f, RACKTIMEOUT);
        pcb->ccp_localstate |= RACK_PENDING;
      } else
        pcb->ccp_localstate |= RREQ_REPEAT;
    }
  }
}
#endif /* PPP_DATAINPUT */

/*
 * We have received a packet that the decompressor failed to
 * decompress. Issue a reset-request.
 */
void ccp_resetrequest(ppp_pcb *pcb) {
  fsm *f = &pcb->ccp_fsm;

  if (f->state != PPP_FSM_OPENED)
    return;

  /*
   * Send a reset-request to reset the peer's compressor.
   * We don't do that if we are still waiting for an
   * acknowledgement to a previous reset-request.
   */
  if (!(pcb->ccp_localstate & RACK_PENDING)) {
    fsm_sdata(f, CCP_RESETREQ, f->reqid = ++f->id, NULL, 0);
    TIMEOUT(ccp_rack_timeout, f, RACKTIMEOUT);
    pcb->ccp_localstate |= RACK_PENDING;
  } else
    pcb->ccp_localstate |= RREQ_REPEAT;
}

/*
 * Timeout waiting for reset-ack.
 */
static void ccp_rack_timeout(void *arg) {
  fsm *f = (fsm *)arg;
  ppp_pcb *pcb = f->pcb;

  if (f->state == PPP_FSM_OPENED && (pcb->ccp_localstate & RREQ_REPEAT)) {
    fsm_sdata(f, CCP_RESETREQ, f->reqid, NULL, 0);
    TIMEOUT(ccp_rack_timeout, f, RACKTIMEOUT);
    pcb->ccp_localstate &= ~RREQ_REPEAT;
  } else
    pcb->ccp_localstate &= ~RACK_PENDING;
}

#endif /* PPP_SUPPORT && CCP_SUPPORT */
